The first thing you need to do when you learn a foreign language is to become familiar with the sounds of the language and how they are written, and the same goes for Lojban. Fortunately, Lojban sounds (phonemes) are fairly straightforward.
There are six vowels in Lojban.
as in father (not as in hat)
as in get
as in machine or (Italian) vino (not as in hit)
as in bold or more — not as in so (this should be a 'pure' sound.)
as in cool (not as in but)
These are pretty much the same as vowels in Italian or Spanish. The sixth vowel, y, is called a schwa in the language trade, and is pronounced like the first and last A's in America (that's English America, not Spanish.) It's the sound that comes out when the mouth is completely relaxed.
Two vowels together are pronounced as one sound (diphthong). Some examples are:
as in high
as in how
as in hey
as in boy
like German Ja
as in waah!, or French quoi
as in question
as in quote
like we, or French oui
Double vowels are rare. The only examples are ii, which is pronounced like English ye (as in "Oh come all ye faithful") or Chinese yi, and uu, pronounced like woo.